Class Mammalia Linnaeus, 1758 - mammals
   Subclass Theria Parker & Haswell, 1897
     Order Perissodactyla Owen, 1848 - odd-toed ungulates
       1 Family Equidae Gray, 1821 [monotypic] - horses, zebras, and asses
       2 Family Tapiridae Gray, 1821 [monotypic] - tapirs
       3 Family Rhinocerotidae Gray, 1821 - rhinoceroses